This paper focuses on the detection of gross error in airborne SAR image coordinates during the process of orientation parameter calculation and stereo positioning. Firstly, based on the range Doppler model, a preliminary discussion is conducted to investigate the impact of image coordinate gross error on the error equations. Secondly, after analyzing the necessity and difficulty of gross detection, based on the quasi-accurate detection, a specific calculation scheme and strategy for orientation parameter calculation is proposed. For the first time, quasi-accurate detection is applied to SAR image orientation. Finally, a series of experiments with both simulated data and real airborne SAR images are carried out to validate the proposed scheme and strategy. The experimental results show that the proposed scheme in this paper is able to detect and calculate the gross errors in image coordinates. Compared to the classical least-square estimation usually used in image orientation, a higher accuracy of both orientation parameters and the subsequent stereo positioning are achieved. The research in this paper is particularly meaningful to improve the quality of the SAR data affected by gross errors in situations where control points are not enough.